1. Field of the Invention
The present invention relates to a lens switch apparatus, and more particularly, to the lens switch apparatus that is rotatable and moveable along X direction or Y direction.
2. Description of the Prior Art
A scanner system becomes a broadly used device, which makes use of focusing a reflected light beam through a photodetector to generate an image signal for further image processing. A conventional scanner system includes a light source, a mirror, and a lens set, which are used to guide the reflected light to an image sensor, such as CCD or CIS.
In order to provide user for several different magnifications, a high-level scanner is designed to be possessed of several lenses, which are switched by a lens switch apparatus. The desired magnification is switched by the lens switch apparatus. Due to the different magnifications, the object length, image length and focal length of each lens having different magnifications is not the same. One disadvantage of the conventional scanner is that large space is required to contain such lenses with the positions fit for their focus lengths.
Referring to FIG. 1(a), which is the top view of a conventional lens switch apparatus, The lens switch apparatus includes a first lens 11, a second lens 12 and a carrier 15. The first lens 11 and the second lens 12, which are positioned on the carrier 15, have a first magnification and a second magnification, respectively. Owing to the magnifications of these lenses are different, the first lens 11 and the second lens 12 are not positioned on the same level. Thus, It results in too large area of the carrier 15. Besides, the carrier 15 moves toward specific direction, such as the horizontal direction in the figure, merely. When the first magnification is required, the first lens 11, on right side of the FIG. 1(a), is aligned to the image sensor 18. While the second magnification is desired, the carrier 15 moves toward the right direction to align the second lens 12 to the image sensor 18. Referring to FIG. 1(b), which depicts the configuration after the carrier 15 moving toward the right direction. Large volume for a scanner is thus needed because the carrier 15 occupies large space for required moving. Moreover, the more the number of lens is, the larger volume of lens switch apparatus requires.
Referring to FIG. 2, which depicts another conventional lens switch apparatus, a round plate is rotated to switch the lens. Several lenses , such as the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, are positioned on the round plate 20. The magnifications of the first lens 21, the second lens 22, the third lens 23 and the fourth lens 24 are the first magnification, the second magnification, the third magnification and the fourth magnification, respectively. In the beginning, the first lens 21 is on the top and aligns to the optical axis 28. While the third magnification is desired, the round plate 20 rotates to make the third lens 23 align to the optical axis 28. The drawback of above mentioned round plate 20 is that large space and large mechanical volume are unavoidable.